Pulpboard



Fatenied Dec. 32, if

, our sass Hubert llZ. Becher, Trenton, Bl. It, assignor to The Auasoteboard ilomuany, Ewing Townshia, N. 3., accretion of? New .llersey NoDrawing.

@riginal application Qctober 30,

1928, Serial No. 318,109. Divided and this application December ll,1930, Serial No. 501,669, and in ilanada @ctoher it), 31929. lB/enewedMay 19, 1933 1 e (or. er -r) My invention relates to a pulpboardcompris=- ing a compressed mixture of fibres, parafin, and Montan wax, asubstantial portion of which is present in the form of a metallic saltof Montan wax, such paramn and metallic salt of Montan wax being presentin a uniform state of distribution and in a fine state of subdivision,which states are obtained when these substances are precipitated from anemulsion prepared from parafin and saponified Montan wax.

Parafin has heretofore been emulsified with the aid of an emulsifyingagent, such as a resin soap or soap prepared from palxnitic or stearicacid. I have found that a better and more suitable emulsion of parafin,useful in the manuiacture of molded pulp board, card board and paper,may be produced by the use oi a soap made oi Montan wax. An emulsionthus produced will retain its stability even in the presence of verylarge amounts of water. Pulp board,

card board or paper sized with this emulsion is therefore very highlywater-proof.

In the manufacture of my new pulp board in accordance with my invention1 have obtained 5 best results with pulp board which is made by heatingpaper pulp, wood pulp, or the like, in a heater, and then running suchpulp into a mold and by means of pressure removing the majority of thewater (see, for instance, United States Letters Patent No. 971,935,dated Gctober i, 191d, and lie. 1,272,568, dated July it, i918), andsubsequentlydrying out the remainder oi the water by the application ofheat.

My preferred method or" preparing the emuls5 sion for use with my newpulp board is to acid from 2il%25% or more, by weight, oi? Montan wax toparafin and then to add to the mixture an alkali, for instance, causticsoda, for saponiiy= ing the Montan wax in quantity suncient to chest ascomplete a saponification oi such was as its nature will permit. Theparafiin and the Montan wax are first melted in hot water and thoroughlyagitated therein until they are broken up as finely as possible; thealkali is then added and the stirring is continued unth substantiallyall the saponiilcation has taken place and the paraffin has beenthoroughly emulsified. The emulsion is then cooled with continuedagitation until the paraffin has become hard. The amount of water usedin this process should be sufiicient to permit the formation of a properemulsion but not much more than this amount. The mixture shoidd bestirred at all times, stirring being particularly advisable during thecooling stage in order that the character of the emulsion may not bedestroyed byagglomeration and settling of the waxes.

Instead of diluting with hot water prior to cooling the emulsion, I maypermit the emulsion to cool and during the cooling stage add cold waterslowly so as to dilute the cooling emulsion gradually about inproportion to what otherwise would be the increase of its viscosity, andwithout suddenly chilling it. .I may also instead .of diluting theemulsion with either hot water or 55 cold water pass it through acolloid mill suitably cooled, thus'efiecting the same result.

The emulsion may be used in the preparation of my pulp board either bymixing the same directly with the paper pulp, preferably in the beater,or by first converting it into an extremely fine suspension by efiectingthe double decoru position thereof with a metallic salt, for instance,magnesium sulfate or aluminum sulfate, thus rendering unnecessary thesubsequent adclltion of a precipitant in the beater, the para and themetallic salts of the saponifled wax being so finely divided that theprecipitant may be added at anearly stage of the fibre treating process.The suspension, moreover, lends itself more readily to prolonged storingand does not crearn asreadily as the emulsion. In the case oi anemulsion, if any paraihn should work its way up to the surface after theemulsion has been allowed to stand, slight agitation will easily $5restore homogeneity.

The precipitant, which may be added during the heating process, is thesame material, for instance, magnesium sulfate or aluminum sulfate. bywhich the line suspension referred to is pro- W duced. The suspensionwill thus contain thev metallic salts of the saponified l flontan waxwhich. are produced when the emulsion is precipitated by the usualprecipitants, namely, the metallic (f. i. aluminum) salt oi the fattyacid (Montan wax) and the metallic salt of the alkali metal (hi.sodium).

As Montan was for some reason apparently not definitely known is notcompletely saponifiable, the saponified Montan was, and the metallicsalt Mm oi l /iontan wax, will contain a substantial ad mixture of anunsaponified ingredient or portion of the Montan wax.

A board thus produced is very highly water- 105 proof and highlydielectric. The proportion or the combined waxes present in the emulsionor suspension to the weight of the fibre in the final product may varywithin wide limits but is preer= ably from 1% to 5% or approximately toi no part of Montan wax and from 1 to 4 parts of parafiin to 100 partsof fibre, dry weight.

Example 100 lbs. of Montan wax and 300 lbs. of paramn are placed into900-1000 lbs. of water heated suficiently to melt both waxes and" thenthor-= oughly stirred. After the waxes have been broken up into fineparticles, 7 lbs. of caustic soda in solution are added gradually andthe heating and stirring are continued for 10-15 minutes after theaddition of the caustic soda has been completed. The emulsion is thencomplete. In order aeeaeie double decomposition of substantially all ofthe Montan wax soap has been efiected. The fibre is then run into amold, and subsequently processed to form the board in the mannerhereinabove referred to.

4 The metallic salt of the alkali metal (f. i. sodium sulfate), beingsoluble in water, is washed out with the drainage water.

This application is a division of my application Serial No. 316,109,filed hot. so, 1928.

I claim:

Pulp board comprising a compressed mixture of about 1 to a parts ofparafin and from to 1 part of Montan wax, a substantial portion of whichis present in the form of a metallic salt of lvlontan wax, to 100 partsof fibre, such paramn and metallic salt of Montan wax being present in auniform state of distribution and in a very' fine I state of subdivisionwhich states are obtained when these substances are precipitated from anemulsion prepared from paraffin and saponified Montan wax. a i I i ERTL. BECKER.

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